Hostage negotiators are on the scene, however there has been no confirmation this is a hostage situation. The Milwaukee bomb squad is also assisting authorities.

Authorities declined to say whether the alleged suspect fled the scene or could be inside the spa, where the shooting occurred. The spa is 9,000 square feet and covers two stories.

Brookfield Police Chief Daniel Tushaus confirmed three people were dead at an afternoon news conference. Four more people were treated with non-critical injuries. The hospital was placed on lock down, with only patients escorted by police being accepted.

The Westmoor Country Club, which shares a parking lot with the spa, has been on lockdown since the incident, said the club's chief operating officer Joe Coen.

"We didn't hear anything but ventured to the north toward the spa and we could clearly see police officers with what looked like to be a rifle and a few attendants were coming out of the building," he said. "We quickly retreated back to the building where authorities have told us to stay."

Coen said he has been "peeking" out of the building and has noticed the same SWAT squads are still in place with their weapon drawn, as they were when he first found out about the situation around noon.

Gov. Scott Walker pledged his support for the victims and the community.

"Senseless acts of violence leave us with heavy hearts and many questions," Walker said in a statement. "Our state will stand with the victims and their families, and we will provide them with the law enforcement and community support they need to heal in the coming days."

This is not the first time a violent shooting has rocked the area.

On Aug. 5, Wade Michael Page, an Army veteran and white supremacist, killed six people and injured three others before fatally shooting himself at a Sikh temple south of Milwaukee.

In 2005, less than a mile away, a gunman killed seven people and wounded four more at a church service at the Sheraton Hotel. Terry Michael Ratzmann, the 44-year-old gunman, then committed suicide.